When a node (i.e., a controllable node) is distant from another node (i.e., a control request node) in a communication system, there is a need for remote control of the controllable node by the control request node. For example, if it is possible for the control request node to activate the controllable node remotely, power consumption can be reduced by putting the controlled node in an idle state (non-active state) for most of the time. Such remote activation of nodes can be realized by an out-of-band scheme using, for example, radio signals. An out-of-band scheme is a procedure of transmitting and receiving signals via a communication link which is different from a usual communication link (i.e., an alternative path).
If it is assumed that there are plural nodes in a communication system, it is desirable to integrate functions such as a function of transmitting various control signals to a controllable node and a function of managing a state of controllable node (for example, active/non-active state), to a proxy node, not to a node individually. According to such a structure, the communication system can be simplified. In such the structure, a control request node can be equated with the proxy node.
To control controllable nodes remotely, a control ID designating an individual controllable node can be used. Herein, there is trade-off regarding the size of a control ID. More specifically, in the communication system, in order to assign the control ID for each controllable node arbitrarily and perform remote control on more controllable nodes individually, more control IDs are required. In other words, it is necessary to increase the bit length of the control ID. However, increased bit length of the control ID would increase the frequency of data error at radio transmission of the control ID (in other words, failure of remote control), increase power consumed by a controlled node to wait and receive a control ID, and increase power consumed by a control node to transmit a control ID.